Various tools, in particular garden tools such as cultivators shovels and rakes, as well as other tools such as squeegees or paint-roller holders are usually provided with relatively short handles. These handles are used whenever the work is relatively close to the user, as for instance when the user is working in the garden on his or her hands and knees, or when cleaning a relatively low window. Nonetheless it is frequently desired to be able to work at some distance from the location where the tool is to engage, as for instance when cultivating in a standing position, when washing a car, or cleaning a relatively high window, or when roller-painting a tall wall or a high ceiling.
Accordingly it is known to provide such tools with extension handles. In the standard systems the extension handle merely has a threaded male projection on one end that fits into a corresponding threaded female recess at the end of the short handle of the tool. Thus the user need merely fix the two together by rotating either the tool or its handle to mount the extension handle firmly on the tool. The disadvantage of this system is that the male projection is relatively short, so that the transmission of lateral or bending forces, as contrasted to longitudinal pressure and tension forces, can lead to deformation of the tool at the connection. Another disadvantage is that the handle must be carefully fitted into and screwed several rotations into the tool for proper mounting. If not screwed all the way in any lateral forces are normally sufficient to damage the screw threads and ruin both the tool and the extension handle.
It has been suggested to overcome some of these disadvantages by providing the extension handle with a relatively long and stepped male projection at its front end that fits into a correspondingly deep and stepped backwardly open female recess. The male projection is provided along its full length with screwthreads of like pitch, so that the large-diameter portion and small-diameter portion of the male part can fit into large-diameter and small-diameter portions of the female part and screw thereinto simultaneously. The system has the considerable disadvantage that it is relatively expensive to manufacture. Furthermore this arrangement once again requires the user to fit the two tools together while aligning the threads and thereafter to laboriously screw the two parts together.